The invention relates to a controller for the drive train of a motor vehicle (drive train controller). The motor vehicle has an engine, a transmission, and an automatically activated clutch. An engine controller controls variables which influence the torque of the engine, and a transmission controller controls the gear-shifting operations of the automatic transmission and exchanges data with the engine controller which permit comfortable operation of the motor vehicle.
In a drive train controller described in my prior U.S. Pat. No. 6,128,564 (see German patent application DE 197 27 044 A1), only physically dimensioned descriptive variables which relate to the required engine torque reduction are exchanged via an interface between the transmission controller and the engine controller. The transmission controller determines the behavior of the engine system on the basis of a generalized model. The model unambiguously describes the behavior required of the transmission controller at the limits of the engine/transmission system (engine output shaft) without relating to the technical implementation in the engine system.
The practical implementation of an intervention into an engine is the responsibility of the engine controller alone. It defines whether an intervention into the ignition has to take place or whether the quantity of fuel injected is reduced or whether the valve control times or valve characteristics are changed or whether the engine is to be controlled by means of the throttle valve. The engine controller alone also controls all the actuators necessary for this purpose. In the known transmission controller, no particular measures are provided for the starting of the motor vehicle.
A prior art automatically actuated clutch is moved by a hydraulic actuator between a fully disengaged position, via positions in which slip occurs in the clutch, into a fully engaged position (see U.S. Pat. No. 5,993,355 and German application DE 44 34 111 A1). The contact point of the clutch is determined and the position assumed here by the actuator is stored. The engine speed at the contact point is regulated to a rotation speed which lies somewhat above the rotational speed of the output shaft of the clutch and the actuator is adjusted to the position corresponding to the contact point.
In a system which is also known for the common control of a servo clutch (assisted clutch) and a vehicle engine, the clutch and the engine are controlled in the range of low vehicle speeds, for example when starting up, in such a way that the position of the accelerator pedal specifies the acceleration or the speed of the vehicle while, outside the starting operation, the drive train is controlled in a power-scaled or torque-scaled fashion as a function of the position of the accelerator pedal (see German patent application DE 197 26 214 A1).
In a device for automatically setting a clutch in a drive train with an engine speed regulating circuit and a clutch torque regulating circuit, the maximum achievable engine torque assuming the highest possible level of engine torque is determined (see German patent DE 196 16 960 C2). A limiter limits the accelerator-pedal-position-dependent setpoint value for the clutch torque regulating circuit to a maximum value which is at maximum as large as the maximum achievable torque communicated to the limiter.
The information which is supplied by a detection circuit for the starting situation and the driver""s characteristics is not taken into account for controlling a starting operation in any of the three last-mentioned controllers.
The invention is based on the object of providing a drive train controller in which automatic starting of the motor vehicle is carried out as reliably and comfortably as possible taking into account the respective starting situation. This drive train controller is provided for motor vehicles with automatic transmission, both of the planetary wheel type and of the CVT type, in particular for those with an automated manual shift transmission in which the driver determines the gear to be engaged or the transmission ratio, but the gear-shifting operation is carried out automatically by the transmission controller.
It is accordingly an object of the invention to provide a drive train controller, which overcomes the above-mentioned disadvantages of the heretofore-known devices and methods of this general type.
With the foregoing and other objects in view there is provided, in accordance with the invention, a controller for a drive train of a motor vehicle having an engine, a transmission, and an automatically activated clutch, comprising:
an engine controller configured to control variables influencing a torque of the engine;
a transmission controller configured to control gear-shifting operations of the automatic transmission and connected to the engine controller for exchanging with the engine controller data permitting a comfortable operation of the motor vehicle;
a detection circuit connected to the transmission controller for determining a respective driving situation of the motor vehicle and a driver""s characteristics;
a control device for controlling the clutch, the control device being adaptively controlled with respect to one of the driving situation determined by the detection circuit and the driver""s characteristics when the motor vehicle starts; and
the control device, when the motor vehicle starts, transferring to the engine controller signals with which the engine speed is controlled according to stored characteristic curves.
In accordance with an added feature of the invention, the detection circuit forms a part of the transmission controller, and the control device forms a part of the transmission controller.
In accordance with an additional feature of the invention, a switching controller is provided for calculating a setpoint wheel torque from a position of an accelerator pedal, the switching controller controlling an engine torque with reference to the setpoint wheel torque.
In accordance with another feature of the invention, the detection circuit for detecting the respective driving situation of the motor vehicle forms a part of the engine controller.
In accordance with a preferred embodiment of the invention, the detection circuit comprises a fuzzy logic system.
In accordance with again an added feature of the invention, a characteristic diagram memory stores characteristic curves for controlling the clutch upon starting and upon maneuvering of the motor vehicle.
In accordance with again an additional feature of the invention, the characteristic diagram memory stores a plurality of characteristic curves corresponding to different starting situations of the motor vehicle.
In accordance with again another feature of the invention, a fuzzy logic system is provided for generating an engine setpoint rotational speed with reference to at least one parameter selected from the group consisting of an engine setpoint torque, a parameter characterizing the driver, and a parameter characterizing a loading of the vehicle.
In accordance with again a further feature of the invention, characteristic curves in the form of a profile of the engine speed are stored in the switching controller as a function of the setpoint engine torque and of the time. Preferably, a rotational speed regulator is contained in the clutch controller for setting a setpoint engine torque with reference to a characteristic curve.
In accordance with a concomitant feature of the invention, the drive train controller is configured with a creeping mode controlled according to a characteristic curve.
The drive train controller of a motor vehicle with an engine and an automatic transmission is provided with an engine controller by means of which variables which influence the torque of the engine are controlled, and with a transmission controller by means of which the gear-shifting operations of the automatic transmission are controlled and by means of which data which makes comfortable operation of the motor vehicle possible is exchanged with the engine controller. Here, the transmission controller is provided with a detection circuit which determines the respective driving situation of the motor vehicle and the driver""s characteristics. It also has a control device for the clutch which is adapted to the driving situation which is determined and/or to the driver""s characteristics when the motor vehicle starts. When the motor vehicle starts, the control device transfers, to the engine controller, signals with which the engine speed is controlled according to stored characteristic curves.
Driving situations are expediently detected with a detection circuit which is embodied as a fuzzy logic circuit. Advanced transmission controllers are in any case frequently provided with fuzzy logic components (see for example F. Graf and H. Weil: Advanced Transmission with Fuzzy Logic, 3rd International Conference, Bologna, Mar. 29-31 1995, Technical Papers pp. 379-89; and U.S. Pat. No. 5,390,117 and European published patent application EP 0 576 703 A1) and can therefore easily be equipped with such a driving situation detection means.
The advantages of the invention are, above all, the improvement which it makes possible in comfort, safety and economy when starting a motor vehicle under a very wide range of ambient conditions, such as when starting on an incline, when maneuvering and when performing parking maneuvers. Further advantages are given in the following description.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a controller for the drive train of a motor vehicle, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.